This invention relates to polymeric dye compositions and methods for their preparation and use.
Many different colorants are commercially available which are used to color polymeric materials, textiles, paper, paint, and the like. These colorants can be classified as either dyes or pigments. Generally, a colorant is considered to be a dye if it is soluble in the medium in which it is used or is applied by a process involving solution formation. Pigments, on the other hand, are generally water insoluble and insoluble in the medium into which they are dispersed.
Although dyes are generally stronger, brighter, and more transparent than pigments, because of their inherent solubility they possess poor migration fastness, especially in plastics. Such migration may take the form of bleeding, blooming, or plateout. Bleeding is the migration of a colorant from one substrate material to an adjacent differently colored or uncolored material as a result of the dye's solubility. Blooming results when the colorant migrates to the surface of a substrate, recrystallizes, and forms a dust-like coating which is easily rubbed off onto adjacent materials. Finally, plateout is characterized by the buildup of a colorant on the metallic surfaces of processing equipment.
Obviously, the above problems with dyes greatly limits their use in plastics, synthetics, and other polymeric materials. Accordingly, the need exists in the art for dyes which exhibit permanence and migration fastness when used as colorants in polymers and the like.